Soft soil foundation treatment method

Abstract

The soft soil foundation treatment method comprises the following steps that S1, construction preparation is conducted, specifically, the geological conditions and construction conditions of a site, the range and thickness of soft soil to be treated and the underground water level are known in detail, and a dynamic compaction machine capable of meeting the dynamic compaction depth and a rapid impact compaction machine are arranged; s2, preparing backfill soil: preparing the backfill soil with different fine particle contents; s3, a contrast test of three tamping modes of dynamic compaction, rapid impact compaction and dynamic compaction and rapid impact combined compaction is carried out; s4, the safety distance between the construction area and the surrounding building is determined; and S5, the backfill soil with the optimal tamping mode and the optimal fine particle content is selected for construction. According to the soft soil foundation treatment method, the bearing capacity of the treated foundation is improved, the liquefaction risk in an earthquake is reduced, and post-construction settlement and differential settlement are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a soft soil foundation treatment method. Background Art

[0002] The soil conditions are mainly loose silt sand in the upper part and dense silt sand in the lower part. It is very easy to liquefy under the action of earthquakes, and the bearing capacity is low and unevenly distributed. Therefore, in the construction of housing, infrastructure, airports, etc., choosing a fast and effective soft soil foundation treatment method has become one of the key factors affecting the quality of the project, the construction period and the cost of the project. The traditional large-area soft soil foundation treatment methods mainly include the strong tamping method of deep compaction and reinforcement of soft soil through impact compaction, the preloading method of accelerating the drainage and consolidation of soft soil by external load, the pile method of transferring the upper load by pile body, and the reinforcement method by adding fiber, new synthetic materials, curing agent and microorganisms. On the one hand, various foundation treatment methods generally do not consider the fine particle content of backfill soil, but only consider the compaction method, resulting in poor bearing capacity of the treated foundation, high risk of liquefaction in earthquakes, and frequent post-construction settlement and uneven settlement. On the other hand, generally only the above-mentioned traditional single foundation treatment method is used, which has factors such as high cost, long construction period, limited reinforcement depth and scope, and difficulty in controlling post-construction settlement and uneven settlement. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a soft soil foundation treatment method which improves the bearing capacity of the treated foundation, reduces the risk of liquefaction in earthquakes, and reduces post-construction settlement and uneven settlement.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A soft soil foundation treatment method comprises the following steps:

[0006] S1. Construction preparation: Understand the geological conditions of the site, construction conditions, the scope and thickness of the soft soil to be treated, and the groundwater level in detail, and equip the compaction machine and rapid impact compactor that can meet the compaction depth;

[0007] S2. Prepare backfill soil: prepare backfill soil with different fine particle contents;

[0008] S3. Comparative test of three compaction methods: strong compaction, rapid impact compaction, and strong compaction and rapid impact combined compaction:

[0009] A test area is selected on the site, and the test area is divided into a strong compaction area, a rapid impact compaction area and a combined compaction area. Each time, a backfill soil with a fine particle content in S2 is used, and a strong compaction test is carried out in the strong compaction area, a rapid impact compaction test is carried out in the rapid impact compaction area, and a combined compaction test is carried out in the combined compaction area until the backfill soil test of each fine particle content is completed;

[0010] The dynamic compaction test is carried out using the dynamic compaction machine in S1: first two times of spot compaction, then full compaction. After each compaction, the site is backfilled and leveled with the backfill soil in S2 before the next compaction. After the last full compaction, the site is backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation.

[0011] The rapid impact compaction test was carried out using the rapid impact compactor in S1: first two times of spot tamping, then full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled to level the site to the designed elevation.

[0012] The combined compaction test was conducted using the dynamic tamping machine and the rapid impact compactor in S1: first, the dynamic tamping machine was used for two spot tampings, and then the rapid impact compactor was used for one rapid impact compaction full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation.

[0013] 7 to 10 days after the completion of the foundation compaction test in the test area, a standard penetration test was carried out to detect the bearing capacity of the foundation, the risk of liquefaction in an earthquake, and the settlement parameters. By comparing the results of the standard penetration test, the best compaction method was obtained as rapid impact combined compaction to obtain backfill soil with the best fine particle content;

[0014] S4. Determine the safe distance between the construction area and surrounding buildings;

[0015] S5. Select the best compaction method and backfill soil with the best fine particle content for construction.

[0016] As a further improvement of the above technical solution:

[0017] In the dynamic compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

[0018] In the dynamic compaction test in S3, the dynamic compaction machine adopts a 2m×2m square compaction hammer with a compaction hammer weight of 23t, a drop height of 20m, 18 compaction times, and a 24-hour interval between each compaction.

[0019] In the rapid impact compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

[0020] In the S3 rapid impact compaction test, the rapid impact compactor uses a 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, 720 strikes, and an interval of 24 hours between each strike.

[0021] In the combined compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

[0022] In the combined compaction test of S3, the dynamic compaction machine uses a 4m 2 The square rammer has a weight of 23t, a drop height of 20m, 18 rammer times, and a 24-hour interval between each rammer. The rapid impact compactor uses a 4m2 square rammer with a total weight of 10t, a maximum rammer stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 rammer times.

[0023] In S2, the fine particle contents of the backfill soil are 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40% respectively; in S3, the optimal fine particle content of the backfill soil is 25%.

[0024] In S4, the safety distance between the construction area and surrounding buildings is greater than 50m.

[0025] In S5, the best compaction method is the combined compaction of strong tamping and rapid impact, and the optimal fine particle content of backfill soil is 25%; first use a strong tamping machine to perform two point tampings, and then use a rapid impact compactor to perform one rapid impact compaction full tamping. After each tamping, use backfill soil with a fine particle content of 25% to backfill and level the site before the next tamping. After the last full tamping, use backfill soil with a fine particle content of 25% to backfill and then roll and level the site to the designed elevation; the strong tamping machine uses a 4m 2 Square rammer, rammer weight 23t, drop height 20m, rammer times 18, each rammer interval 24 hours; point ramming points are arranged in a square, the first point ramming distance is 7m×7m, the second point ramming distance is 4.95m×4.95m; fast impact compactor uses 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 strikes.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] The soft soil foundation treatment method of the present invention takes into account both the fine particle content of the backfill soil and the compaction method. On the one hand, by conducting comparative tests on backfill soil with different fine particle contents and three compaction methods, namely, strong compaction, rapid impact compaction, and strong compaction and rapid impact combined compaction, the best compaction method and the backfill soil with the best fine particle content are obtained, and then the best compaction method and the backfill soil with the best fine particle content are selected for construction, thereby improving the bearing capacity of the treated foundation, reducing the risk of liquefaction in earthquakes, and reducing post-construction settlement and uneven settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the soft soil foundation treatment method of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "assemble", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Figure 1 An embodiment of the soft soil foundation treatment method of the present invention is provided. The soft soil foundation treatment method of this embodiment comprises the following steps:

[0034] S1. Construction preparation: Understand the geological conditions of the site, construction conditions, the scope and thickness of the soft soil to be treated, and the groundwater level in detail, and equip the compaction machine and rapid impact compactor that can meet the compaction depth;

[0035] S2. Prepare backfill soil: prepare backfill soil with different fine particle contents;

[0036] S3. Comparative test of three compaction methods: strong compaction, rapid impact compaction, and strong compaction and rapid impact combined compaction:

[0037] A test area is selected on the site, and the test area is divided into a strong compaction area, a rapid impact compaction area, and a combined compaction area. Each time, the backfill soil with the fine particle content in S2 of this embodiment is used, and a strong compaction test is performed in the strong compaction area, a rapid impact compaction test is performed in the rapid impact compaction area, and a combined compaction test is performed in the combined compaction area until the backfill soil test of each fine particle content is completed;

[0038] The dynamic compaction test is carried out using the dynamic compaction machine in S1: first two times of spot compaction, then full compaction. After each compaction, the site is backfilled and leveled with the backfill soil in S2 before the next compaction. After the last full compaction, the site is backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation.

[0039] The rapid impact compaction test was carried out using the rapid impact compactor in S1: first two times of spot tamping, then full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled to level the site to the designed elevation.

[0040] The combined compaction test was conducted using the dynamic tamping machine and the rapid impact compactor in S1: first, the dynamic tamping machine was used for two spot tampings, and then the rapid impact compactor was used for one rapid impact compaction full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation.

[0041] 7 to 10 days after the completion of the foundation compaction test in the test area, a standard penetration test was carried out to detect the bearing capacity of the foundation, the risk of liquefaction in an earthquake, and the settlement parameters. By comparing the results of the standard penetration test, the best compaction method was obtained as rapid impact combined compaction to obtain backfill soil with the best fine particle content;

[0042] S4. Determine the safe distance between the construction area and surrounding buildings;

[0043] S5. Select the best compaction method and backfill soil with the best fine particle content for construction.

[0044] This soft soil foundation treatment method takes into account both the fine particle content of the backfill soil and the compaction method. On the one hand, by conducting comparative tests on backfill soil with different fine particle contents and three compaction methods, namely, strong tamping, rapid impact compaction, and strong tamping and rapid impact combined compaction, the best compaction method and the best fine particle content backfill soil are obtained. Then, the best compaction method and the best fine particle content backfill soil are selected for construction, thereby improving the bearing capacity of the treated foundation, reducing the risk of liquefaction in earthquakes, and reducing post-construction settlement and uneven settlement.

[0045] Furthermore, in the present embodiment, in the dynamic compaction test in S3, the tamping points are arranged in a square, the tamping distance for the first time is 7m×7m, and the tamping distance for the second time is 4.95m×4.95m.

[0046] Furthermore, in the dynamic compaction test in S3 of the present embodiment, the dynamic compaction machine adopts a 2m×2m square compaction hammer, the compaction hammer weighs 23t, the drop height is 20m, the number of compaction times is 18, and the interval between each compaction is 24 hours.

[0047] Furthermore, in the present embodiment, in the rapid impact compaction test in S3, the tamping points are arranged in a square, the tamping distance for the first time is 7m×7m, and the tamping distance for the second time is 4.95m×4.95m.

[0048] Furthermore, in this embodiment, in the rapid impact compaction test in S3, the rapid impact compactor uses a 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, 720 strikes, and an interval of 24 hours between each strike.

[0049] Furthermore, in the present embodiment, in the combined compaction test in S3, the tamping points are arranged in a square, the tamping distance for the first time is 7m×7m, and the tamping distance for the second time is 4.95m×4.95m.

[0050] Furthermore, in this embodiment, in the combined compaction test in S3, the dynamic compaction machine uses a 4m 2 The square rammer has a weight of 23t, a drop height of 20m, 18 rammer times, and a 24-hour interval between each rammer. The rapid impact compactor uses a 4m2 square rammer with a total weight of 10t, a maximum rammer stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 rammer times.

[0051] Furthermore, in this embodiment, in S2, the fine particle content of the backfill soil is 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40%, respectively; and in S3, the optimal fine particle content of the backfill soil is 25%.

[0052] Specifically, the strong compaction area, rapid impact compaction area and combined compaction area can be divided into areas 1 to 8:

[0053] In the first comparative experiment, backfill soil with a fine particle content of 5% was used to conduct a dynamic compaction test in the No. 1 dynamic compaction area, a rapid impact compaction test in the No. 1 rapid impact compaction area, and a combined compaction test in the No. 1 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 5% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 5% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two point tampings were performed, followed by one full tamping. After each tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 5% before the next tamping. After the last full tamping, the site was backfilled with backfill soil with a fine particle content of 5%, and then the site was rolled and leveled to the designed elevation. The combined compaction test was performed using the dynamic tamping machine and rapid impact compactor in S1: first, two point tampings were performed with the dynamic tamping machine, and then one rapid impact compaction and full tamping was performed with the rapid impact compactor. After each tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 5% before the next tamping.

[0054] In the second comparative experiment, backfill soil with a fine particle content of 10% was used to conduct a dynamic compaction test in the No. 2 dynamic compaction area, a rapid impact compaction test in the No. 2 rapid impact compaction area, and a combined compaction test in the No. 2 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 10% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 10% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 10% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 10% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 10% before the next tamping was carried out.

[0055] In the third comparative experiment, backfill soil with a fine particle content of 15% was used to conduct a dynamic compaction test in the No. 3 dynamic compaction area, a rapid impact compaction test in the No. 3 rapid impact compaction area, and a combined compaction test in the No. 3 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 15% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 15% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 15% before the next tamping. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 15% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 15% before the next tamping.

[0056] In the fourth comparative experiment, backfill soil with a fine particle content of 20% was used to conduct a dynamic compaction test in the No. 4 dynamic compaction area, a rapid impact compaction test in the No. 4 rapid impact compaction area, and a combined compaction test in the No. 4 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 20% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 20% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 20% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 20% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 20% before the next tamping was carried out.

[0057] In the fifth comparative experiment, backfill soil with a fine particle content of 25% was used to conduct a dynamic compaction test in the No. 5 dynamic compaction area, a rapid impact compaction test in the No. 5 rapid impact compaction area, and a combined compaction test in the No. 5 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 25% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 25% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 25% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 25% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 25% before the next tamping was carried out.

[0058] In the sixth comparative experiment, backfill soil with a fine particle content of 30% was used to conduct a dynamic compaction test in the No. 6 dynamic compaction area, a rapid impact compaction test in the No. 6 rapid impact compaction area, and a combined compaction test in the No. 6 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 30% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 30% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 30% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 30% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 30% before the next tamping was carried out.

[0059] In the seventh comparative experiment, backfill soil with a fine particle content of 35% was used to conduct a dynamic compaction test in the No. 7 dynamic compaction area, a rapid impact compaction test in the No. 7 rapid impact compaction area, and a combined compaction test in the No. 7 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 35% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 35% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 35% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 35% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 35% before the next tamping was carried out.

[0060] In the eighth comparative experiment, backfill soil with a fine particle content of 40% was used to conduct a dynamic compaction test in the No. 8 dynamic compaction area, a rapid impact compaction test in the No. 8 rapid impact compaction area, and a combined compaction test in the No. 8 combined compaction area; the dynamic compaction test was conducted using the dynamic compaction machine in S1: first two point compactions and then full compaction. After each compaction, the site was backfilled and leveled with backfill soil with a fine particle content of 40% before the next compaction. After the last full compaction, the site was backfilled with backfill soil with a fine particle content of 40% and then rolled to the designed elevation; the rapid impact compaction test was conducted using the dynamic compaction machine in S1. The rapid impact compactor in S1 was used for the combined compaction test: first, two times of spot tamping and then one time of full tamping. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 40% before the next tamping was carried out. After the last time of full tamping, the site was backfilled with backfill soil with a fine particle content of 40% and then rolled to the designed elevation. The combined compaction test was carried out using the dynamic tamping machine and rapid impact compactor in S1: first, two times of spot tamping were carried out with the dynamic tamping machine, and then one time of rapid impact compaction and full tamping was carried out with the rapid impact compactor. After each time of tamping, the site was backfilled and leveled with backfill soil with a fine particle content of 40% before the next tamping was carried out.

[0061] 7 to 10 days after the completion of the foundation compaction test in each test area, a standard penetration test is carried out to detect the bearing capacity of the foundation, the liquefaction risk in an earthquake, and the settlement parameters; through comparison of the results of the standard penetration test, the best compaction method is obtained as rapid impact combined compaction to obtain backfill soil with the best fine particle content.

[0062] Furthermore, in this embodiment, in S4, the safety distance between the construction area and surrounding buildings is greater than 50m.

[0063] Furthermore, in this embodiment, in S5, the best compaction method is the combined compaction of strong tamping and rapid impact, and the optimal fine particle content of the backfill soil is 25%; first, a strong tamping machine is used to perform two point tampings, and then a rapid impact compactor is used to perform a rapid impact compaction full tamping. After each tamping, the backfill soil with a fine particle content of 25% is used to backfill and level the site before the next tamping. After the last full tamping, the backfill soil with a fine particle content of 25% is used to backfill and then the site is rolled and leveled to the designed elevation; the strong tamping machine uses 4m 2 Square rammer, rammer weight 23t, drop height 20m, rammer times 18, each rammer interval 24 hours; point ramming points are arranged in a square, the first point ramming distance is 7m×7m, the second point ramming distance is 4.95m×4.95m; fast impact compactor uses 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 strikes.

[0064] Furthermore, in this embodiment, the thickness of the backfill soil used for backfilling after each tamping is 0.5-6.0 m. The backfill soil has a fine particle content of 25% (passing a No. 200 sieve), a clay content of less than 2%, a maximum particle size of 200 mm, does not contain organic matter and harmful substances, and has good water stability.

[0065] Furthermore, in this embodiment, the size of the test area is selected to be 6000m 2 .

[0066] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for treating soft soil foundation, characterized in that: The steps include: S1. Construction preparation: Understand the geological conditions of the site, construction conditions, the scope and thickness of the soft soil to be treated, and the groundwater level in detail, and equip the compaction machine and rapid impact compactor that can meet the compaction depth; S2. Prepare backfill soil: prepare backfill soil with different fine particle contents; S3. Comparative test of three compaction methods: strong compaction, rapid impact compaction, and strong compaction and rapid impact combined compaction: A test area is selected on the site, and the test area is divided into a strong compaction area, a rapid impact compaction area and a combined compaction area. Each time, a backfill soil with a fine particle content in S2 is used, and a strong compaction test is carried out in the strong compaction area, a rapid impact compaction test is carried out in the rapid impact compaction area, and a combined compaction test is carried out in the combined compaction area until the backfill soil test of each fine particle content is completed; The dynamic compaction test is carried out using the dynamic compaction machine in S1: first two times of spot compaction, then full compaction. After each compaction, the site is backfilled and leveled with the backfill soil in S2 before the next compaction. After the last full compaction, the site is backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation. The rapid impact compaction test was carried out using the rapid impact compactor in S1: first two times of spot tamping, then full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled to level the site to the designed elevation. The combined compaction test was conducted using the dynamic tamping machine and the rapid impact compactor in S1: first, the dynamic tamping machine was used for two spot tampings, and then the rapid impact compactor was used for one rapid impact compaction full tamping. After each tamping, the site was backfilled and leveled with the backfill soil in S2 before the next tamping. After the last full tamping, the site was backfilled with the backfill soil in S2 and then rolled and leveled to the designed elevation. 7 to 10 days after the completion of the foundation compaction test in the test area, a standard penetration test was carried out to detect the bearing capacity of the foundation, the risk of liquefaction in an earthquake, and the settlement parameters. By comparing the results of the standard penetration test, the best compaction method was obtained as rapid impact combined compaction to obtain backfill soil with the best fine particle content; S4. Determine the safe distance between the construction area and surrounding buildings; S5. Select the best compaction method and backfill soil with the best fine particle content for construction.

2. The soft soil foundation treatment method according to claim 1, characterized in that: In the dynamic compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

3. The soft soil foundation treatment method according to claim 2, characterized in that: In the dynamic compaction test in S3, the dynamic compaction machine adopts a 2m×2m square compaction hammer with a compaction hammer weight of 23t, a drop height of 20m, 18 compaction times, and a 24-hour interval between each compaction.

4. The soft soil foundation treatment method according to claim 1, characterized in that: In the rapid impact compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

5. The soft soil foundation treatment method according to claim 4, characterized in that: In the S3 rapid impact compaction test, the rapid impact compactor uses a 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, 720 strikes, and an interval of 24 hours between each strike.

6. The soft soil foundation treatment method according to claim 1, characterized in that: In the combined compaction test in S3, the tamping points were arranged in a square, the tamping distance for the first time was 7m×7m, and the tamping distance for the second time was 4.95m×4.95m.

7. The soft soil foundation treatment method according to claim 6, characterized in that: In the combined compaction test of S3, the dynamic compaction machine uses a 4m 2 Square rammer, rammer weight 23t, drop height 20m, rammer times 18, each rammer interval 24 hours; fast impact compactor uses 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 strikes.

8. The soft soil foundation treatment method according to any one of claims 1 to 7, characterized in that: In S2, the fine particle contents of the backfill soil are 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40% respectively; in S3, the optimal fine particle content of the backfill soil is 25%.

9. The soft soil foundation treatment method according to any one of claims 1 to 7, characterized in that: In S4, the safety distance between the construction area and surrounding buildings is greater than 50m.

10. The soft soil foundation treatment method according to any one of claims 1 to 7, characterized in that: In S5, the best compaction method is the combined compaction of strong tamping and rapid impact, and the optimal fine particle content of backfill soil is 25%; first use a strong tamping machine to perform two point tampings, and then use a rapid impact compactor to perform one rapid impact compaction full tamping. After each tamping, use backfill soil with a fine particle content of 25% to backfill and level the site before the next tamping. After the last full tamping, use backfill soil with a fine particle content of 25% to backfill and then roll and level the site to the designed elevation; the strong tamping machine uses a 4m 2 Square rammer, rammer weight 23t, drop height 20m, rammer times 18, each rammer interval 24 hours; point ramming points are arranged in a square, the first point ramming distance is 7m×7m, the second point ramming distance is 4.95m×4.95m; fast impact compactor uses 4m 2 The square rammer has a total weight of 10t, a maximum stroke of 1.2m, a hammer frequency of 48 times / minute, and 720 strikes.

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